#include <iostream>
#include <string>
#include <cerrno>  // C++版本的errno.h
#include <cstring> // C++版本的string.h
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

const int size = 1024;

std::string GetOtherMessage()
{
    static int count = 0;
    std::string messageid = std::to_string(count);
    count++;
    pid_t self_id = getpid();
    std::string stringid = std::to_string(self_id);
    std::string message = "messageid: ";
    message += messageid;
    message += " my pid is : ";
    message += stringid;

    return message;
}

void SubProcessWrite(int wfd)
{
    int pipesize = 0;
    std::string message = "Father,I am your child process~";
    char c = 'A';
    while(true)
    {
        std::cerr << "++++++++++++++++++++++++++++" << std::endl;
        std::string info = message + GetOtherMessage();//这条消息，就是我们子进程发给父进程的消息
        write(wfd,info.c_str(),info.size());   

        std::cerr << info <<std::endl;
        //sleep(1);  //子进程写慢一点

        // write(wfd,&c,1);
        // std::cout<<"pipesize: "<<++pipesize<< " write charactor is : "<< c << std::endl;
        // c++;
        // //if(c=='G') break;
        // sleep(1);
    }
    std::cout<<"child quit..."<<std::endl;
}

void FatherProcessRead(int rfd)
{
    sleep(2);
    std::cout<<"-------------------------------"<<std::endl;
    char inbuffer[size]; //c99 
    while(true)
    {
        ssize_t n = read(rfd,inbuffer,sizeof(inbuffer)-1);
        if(n>0)
        {
            inbuffer[n] = 0;// '\0'
            std::cout<<inbuffer<< std::endl;
        }
        //如果read的返回值是0，表示写端关闭了，我们读到了文件的结尾
        else if(n==0)
        {
            std::cout<<"client quit, father get return val: "<< n << "father quit too!"<< std::endl;
            break;
        }
        else
        {
            std::cerr << "read error" << std::endl;
            break;
        }
        sleep(1);
    }
}

int main()
{
    close(0);
    //1.创建管道
    int pipefd[2];
    int n = pipe(pipefd);// 输出型参数，rfd wfd
    if(n != 0)
    {
        std::cerr<<"errno: "<<errno<<": "<<"errstring: "<<strerror(errno)<<std::endl;
        return 1;
    }

    std::cout<<"pipefd[0]:"<<pipefd[0]<<",pipefd[1]:"<<pipefd[1]<<std::endl;
    sleep(1);

    //2.创建子进程
    pid_t id = fork();
    if(id == 0)
    {
        std::cout<<"子进程关闭不需要的fd了，准备发消息了"<<std::endl;
        sleep(1);
        //子进程 -- write
        //3.关闭不需要的fd
        close(pipefd[0]);
        SubProcessWrite(pipefd[1]);

        close(pipefd[1]);

        exit(0);
    }
    std::cout<<"父进程关闭不需要的fd了，准备收消息了"<<std::endl;
    sleep(1);
    //父进程  -- read
    //3.关闭不需要的fd
    close(pipefd[1]);
    FatherProcessRead(pipefd[0]);
    std::cout << "5s, father close rfd" << std::endl;
    sleep(5);
    close(pipefd[0]);

    int status = 0;
    pid_t rid = waitpid(id,&status,0);
    if(rid > 0)
    {
        std::cout<<"wait child process done, exit sig: "<< (status & 0x7f) << std::endl;
        std::cout<<"wait child process done, exit code(ign): "<< ((status>>8)&0xFF) << std::endl;
    }

    return 0;
}

